High strength hook, in particular for elastic cable

ABSTRACT

The invention relates to a high strength hook. The hook comprises an annular metal insert ( 3 ) embedded in a synthetic material end block of the hook around a passage ( 4 ) for slidably receiving the end of a cable ( 5 ) in the vicinity of a stop abutment ( 4   c ) designed to stop the end of the cable in the traction direction. The invention is applicable to hooks comprising a metal hook having an end embedded in a handle block.

FIELD OF THE INVENTION

The present invention relates to a hook of the type having, at one end,a handle block of synthetic material shaped to facilitate taking hold ofthe hook and having a passage passing therethrough for receiving andretaining in the block a cable to which the hook is to be fixed.

BACKGROUND OF THE INVENTION

Such a hook is described in publication U.S. Pat. No. 5,317,788, forexample.

To retain the cable in the hook when traction is applied to the cabletending to extract it from the hook, the passage tapers so as to definean abutment for stopping the end of the cable once said end has beenenlarged after being passed through the passage. In the embodimentdescribed in the above-specified publication, the end of the cable isenlarged by folding the end back onto the cable and by holding the endin place in a metal ring, and the passage through the block is designedso as to receive the enlarged end of the cable when traction is appliedto the cable in a direction tending to extract it from the hook, suchthat the enlarged end comes to bear against the abutment which stops it(FIGS. 4 and 5).

When very high levels of traction are applied, that retention can beinsufficient.

An object of the present invention is to improve that retaining device.

According to the present invention, this is achieved by embedding anannular metal insert in the block around said passage, in the vicinityof said taper.

In a preferred embodiment, the insert constitutes one end ofreinforcement which extends over the full length of the hook, therebyfurther improving the strength of the hook

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of such a hook is described below with reference to thefigures of the accompanying drawings, in which:

FIG. 1 is a diagrammatic perspective view of the reinforcement of thehook;

FIG. 2 is a section of the hook including the axis of the passagethrough the handle block;

FIG. 3 is a longitudinal section of the hook fixed to a cable;

FIG. 4 is a diagrammatic perspective view of the crimped end of a cableretained in the passage of the handle block;

FIG. 5 is a perspective view of the hook provided with a safety tongue;

FIG. 6 is a view of the hook on a plane perpendicular to the planecontaining the curve of the hook; and

FIGS. 7 and 8 relate so detail variants.

DETAILED DESCRIPTION OF THE INVENTION

In each case, the scale of the figures is appropriate for thecorresponding explanations.

The reinforcement (A) of the hook is constituted (see FIG. 1) by a rigidmetal wire (A) having one end (1) curved into an upside-down J-shape andhaving its other end bent so as to lie in a plane perpendicular to theplane of the J-shape and curved so as to form an open or closed ring (3)therein.

The hook is preferably made of steel flat with an optionally roundededge, the hook being formed edgewise so as to provide the greatestpossible strength.

The ring (3) is substantially on the same axis as the top (S) of thecurve of the J-shape and the shank (2) of the J-shape slopes slightlyoutwards going away from the ring.

This wire is placed in the cavity of an injection mold so as to becoated in a synthetic resin or some other suitable material. For thisoperation, it is possible for example to use polyethylene orpolypropylene for conventional hooks, or a polyamide or a reinforcedpolyamide for hooks that need to withstand abrasion.

The cavity is shaped so that the injected material (M) (FIG. 2) fitsclosely to the J-shaped portion (1) of the wire and to the shank (2),while being much thicker around the base (2′) of the shank (2) andaround the ring (3) of the wire so as to provide a finger grip block (B)having a through passage (4) whose axis is in line with the top of thecurve of the J-shape.

The overall thickness of the block in a plane perpendicular to the planeof the J-shape of the hook can, for example, be three to five times thethickness of the coated shank and it is four to eight times saidthickness in a plane parallel to the plane of the J-shape, given theprojecting portions presented by the block.

The passage (4) forms an inlet duct (4 a) which is cylindrical, forexample, through which the end of a cable (5), preferably an elasticcable, is inserted into the hook, and it also forms an outlet duct (4 b)whose shape is frustoconical, for example, opening out so as to face thecurve of the J-shape, with the junction between the two ducts forming ashoulder (4 c) which constitutes an abutment.

The mold cavity is designed so that the metal wire ring (3) iscompletely embedded in the injected material (M) and is situated aroundthe inlet duct (4 a) close to the shoulder (4 c)

In a conventional manner, the end of the cable (5) is folded back ontoitself and is crimped by means of a metal clip (6), e.g. a steel ringwhich is flattened after crimping. When traction is applied to thecable, this crimped end bears against the junction (4 c) between the twoducts as reinforced by the ring (3) of the wire (1) (FIGS. 3 and 4).

The invention is not limited to using a clip for fitting to the end ofthe cable. It can be substituted by any means capable of maintaining theenlarged end of the cable.

The inlet edge (9) of the inlet duct (4 a) is rounded so as to avoid thepresence of any sharp edge which could injure the cable.

This advantage does not exist in hooks where the synthetic material ismolded directly onto the cable since under such circumstances:

-   -   the plastics material becomes embedded in the cable, giving rise        to sharp edges that can injure it; and    -   contact between the molten material and the synthetic covering        of the cable can degrade the covering.

The mold cavity is designed so that the finger grip block (B) is of anydesired ergonomic shape, e.g. having lateral recesses (a, b, c, d)enabling the hook to be held between the fingers, together withprojecting portions (e, f) against which the fingers can bear. Thelateral recesses can be made in portions of the block which project fromthe block, such as the recess (a) situated beside the shank (2).

The projecting portion (e) which faces the end (E) of the hook servesfor guidance purposes while the hook is being engaged on a bar or on anyother part onto which it is to be hooked.

The molded block (B) can carry a pivoting safety tongue (7) suitable forbearing against the inside of the free end (E) of the hook (FIG. 5), inconventional manner.

A plug can close the inlet to the passage (4 a) around the cable,thereby giving the hook a finished appearance.

The free end (E) of the hook can receive very effective protection bybeing coated with an extra thickness of material (FIG. 7).

A ring handle (8) can be provided to make the hook easier to use in somecases (FIG. 8).

The strength of the hook is such that it can receive bars of largedimensions (P) and (P₁), whereas with a standard hook these dimensionsmust be restricted so as to avoid weakening the ability of the hook towithstand being prized open.

Another, non-negligible advantage of the invention lies in thepossibility of regularly inspecting the quality of the crimping and thequality of the elastic, which is not possible with hooks that are moldeddirectly onto the cable.

It will also be observed that the coating material does not have anyholes, whereas in earlier devices, the locations of parts for holdingthe metal core in the mold leave the core visible at certain locationsof the over-molded product, thereby requiring the locations to beprovided with additional protection so as to avoid oxidation andswelling of the core, which could possibly lead to the coating beingdestroyed.

The invention is not limited to the embodiment described but extends toany variant that can be obtained by replacing the means described withmeans that are functionally equivalent.

1. A hook for a cable comprising: a finger grip end block having apassage formed therethrough; a solid cable slidably resting in thepassage, the cable having a folded end secured by a crimped clip; thepassage having a circular inlet duct through which a straightened cablesection passes; the passage further having an outlet duct, larger thanthe inlet duct and receiving the folded cable end; a junction betweenthe inlet and outlet ducts forming a shoulder serving as a stop abutmentfor the folded cable end when the cable is placed in tension; a rigidflat metal wire having an inverted J-shaped first end section facing theoutlet duct, the inverted J-shaped first end section serving as a hookmember, and the flat wire having an opposite end section bent into aring embedded in the finger grip block, around the stop abutment, andlocated in a plane generally perpendicular to the J-shaped first endsection, the ring serving to reinforce the shoulder that serves as astop abutment; and wherein the ring surrounds said inlet duct in thevicinity of its junction with the outlet duct.
 2. A hook according toclaim 1, in which said ring has an axis passing through a top of a curveof the J-shaped first end section.
 3. A hook according to claim 1, inwhich an inlet edge of the inlet duct is rounded so as to avoid leavingany sharp edge which could injure the cable.
 4. A hook according toclaim 1, in which the finger grip end block has lateral recesses andprojections to form a finger grip.
 5. A hook according to claim 1, inwhich the finger grip end block connects a tilting safety tongue fixedto said finger grip end block for bearing against a free inside end ofthe hook.
 6. A hook according to claim 5, in which a free end is coatedwith extra injected material.
 7. The hook according to claim 1, whereinan outer circular end of the inlet duct is outwardly flared to avoid asharp edge from contacting the cable.
 8. The hook according to claim 1,wherein the overall thickness of the block in a plane perpendicular tothe plane of the J-shaped first end section is 3-5 times the thicknessof the coated shank, and is 4-8 times said thickness in a plane parallelto the plane of the J-shaped end section.